1. Field of the Invention
This document relates to semiconductor devices, method for manufacturing semiconductor devices, and method for forming oxide films.
Note that a semiconductor device in this specification refers to general devices which can function by utilizing semiconductor characteristics; for example, a semiconductor element such as a transistor, a semiconductor circuit including a semiconductor element, an electro-optical device such as a display device, and an electronic device are all semiconductor devices.
2. Description of the Related Art
Transistors used for most flat panel displays typified by a liquid crystal display device and a light-emitting display device are formed using silicon semiconductors such as amorphous silicon, single crystal silicon, and polycrystalline silicon provided over glass substrates. Further, transistors formed using such silicon semiconductors are used in integrated circuits (ICs) and the like.
In recent years, attention has been drawn to a technique of using, instead of a silicon semiconductor, a metal oxide exhibiting semiconductor characteristics for transistors. Note that in this specification, a metal oxide exhibiting semiconductor characteristics is referred to as an oxide semiconductor.
For example, a technique of using an oxide semiconductor containing at least one element selected from indium (In), gallium (Ga), and zinc (Zn) for a transistor is disclosed (see Patent Document 1 and Patent Document 2).
In addition, a technique of forming an oxide semiconductor which contains zinc oxide as a main component by sputtering while supplying a gas containing oxygen and supplying bias power to the substrate side is disclosed (see Patent Document 3).